I have sold an item which the buyer asked to collect, purchased and then changed their mind and wanted it posting. I can't see how to do the postage side of things as everything on the order relates to arranging the collection.
You would have to cancel and relist with postage. Click on the dropdown menu arrow alongside the item on your orders page and select Cancel order > Buyer asked to cancel. Refund will be issued in the process, if the buyer has paid.
